PCB & Library Calculators

⭕

Annular Ring (IPC-2221)

PCB / Library Design

Pad diameter land

mm

Finished hole diameter after plating

mm

Performance class

Class 2 Class 3

Producibility level registration

A · Low B · Std C · High

—

Actual annular ring —mm

Required AR (min) —mm

Margin —mm

Recommended min pad —mm

Reference

AR = (D_pad − D_hole) / 2. IPC-2221B §9.1 requires 0.05 mm min external AR for Class 2 & 3. Producibility levels add A: 0.10, B: 0.05, C: 0.025 mm per side for hole-to-land registration. Class 3 adds 0.025 mm safety margin against breakout.

🟢

Solder Mask Expansion

Library / Footprint Design

Pad diameter

mm

Pad pitch centre-to-centre

mm

Mask style

NSMD SMD Gang

Expansion per side

mm

Performance class

Class 2 Class 3

—

Mask aperture —mm

Mask web (gap between openings) —mm

Min web (fab limit) —mm

Recommendation —

Reference

NSMD: aperture = pad + 2·e. SMD: aperture = pad − 2·e. Typical e: Class 2 = 0.075 mm, Class 3 = 0.05 mm. Mask web min: 0.075 mm (Cl 2) / 0.10 mm (Cl 3). Below that → gang the pads.

⬛

Paste Mask Reduction

Stencil / DFM (IPC-7525)

Thermal pad size (L × W)

L

W

Target paste coverage

%

Stencil thickness

Aperture grid (N × M)

N

M

—

Aperture side —mm

Web width (X / Y) —mm

Actual coverage —%

IPC-7525 area ratio —≥ 0.66

Reference

a = √(coverage·L·W / N·M). Area ratio = a / (4·t) for square apertures (IPC-7525B §4). AR < 0.66 → paste release failure. Web should be ≥ 0.2 mm so the stencil supports between openings.

📏

Stackup Impedance

Signal Integrity / Hammerstad-Jensen

Geometry

Microstrip Stripline

Trace width (w)

mm

Dielectric height (h) to plane

mm

Copper thickness (t)

Dielectric constant (εr)

—

Pair spacing (s) edge-to-edge

mm

Target impedance

Ω

—

Single-ended Z₀ —Ω

Differential Z_diff —Ω

Δ from target —%

Effective εr —

Validity —

Reference

Microstrip uses Hammerstad-Jensen with thickness correction (Saturn-toolkit grade, ±2 % vs commercial field solver). Stripline uses IPC-2141A closed form. Differential: Z_diff = 2·Z₀(1 − 0.48·e^−0.96s/h). For tape-out, confirm with a 2-D solver (Polar Si9000, HyperLynx).

📚

Copper Balance / Pour Density

Stackup / Warpage DFM

—

Warpage risk —

Max pairwise Δ —%

Average density —%

Reference

Pairwise |Δ| between symmetric layers (L1↔Ln, L2↔Ln-1 …). Δ < 10 % → LOW; 10–20 % → MEDIUM; > 20 % → HIGH risk. Asymmetric copper causes warpage during reflow; add balancing pours to flagged layers.

🕳️

Drill Aspect Ratio

Fabrication / IPC-2226

Via type

PTH Buried Blind µVia

Board thickness PTH only

mm

Segment thickness buried / blind / µvia

mm

Drill diameter

mm

—

Aspect ratio —: 1

Standard fab limit —: 1

Advanced fab limit —: 1

Effective depth —mm

Reference

PTH: 8:1 std / 10:1 adv · Buried: 6:1 / 8:1 · Blind (mech.): 0.8:1 / 1.0:1 · µVia (laser): 0.75:1 / 1.0:1 (IPC-2226 Type I/II/III). Exceeding standard → premium fab quote, longer lead time.